Eleven bodies were recovered in the sea about 400 miles from the Brazilian archipelago of Fernando de Noronha today as the search continued for the remains of the 228 people aboard the doomed Air France jet that disappeared off Brazil's north-east coast last Monday.

The recovery of the bodies came after a night of "intense activity" by the fleet of 14 aeroplanes, five naval ships and one French vessel deployed to scour the remote waters around Fernando de Noronha, amid fears that deteriorating weather over the next 24 hours may hamper recovery operations.

A total of 17 bodies have now been recovered after the remains of six were found on Saturday. Authorities said pilots searching the mid-Atlantic also spotted an undetermined number of additional bodies from the air and were sending ships to recover them.

Flight 447 disappeared in turbulent weather on 31 May during a flight from Rio de Janeiro to Paris with 228 people aboard – all now presumed dead. The investigation is increasingly focused on whether external instruments may have iced over, confusing speed sensors and leading computers to set the plane's speed too fast or slow – a potentially deadly mistake.

The French agency investigating the disaster said airspeed instruments on the plane had not been replaced as the maker had recommended, but warned that it was too early to draw conclusions about what role that may have played in the crash.

The agency, BEA, said the plane received inconsistent airspeed readings from different instruments as it struggled in a huge thunderstorm.

In Brazil, Air Force Colonel Henry Munhoz said he could not immediately provide information on how many more bodies were spotted from the air.

An initial four bodies were found yesterday about 45 miles from the point where the jet sent out a burst of messages indicating it was experiencing a series of electrical failures and losing cabin pressure.

Authorities also said that searchers had spotted two plane seats and other debris with Air France's logo, and have recovered wing fragments and other debris. Munhoz said there was "no more doubt" that the wreckage was from Flight 447.

Hundreds of personal items belonging to passengers have been recovered, but Munhoz said the authorities would not immediately identify them, after the reaction of relatives when authorities yesterday announced the discovery of a laptop computer and a briefcase with a plane ticket inside it. "We don't want to cause them more suffering," Munhoz said.

The bodies and plane wreckage will be transported tomorrow to Fernando de Noronha, where the military has set up a staging post for the search operation. From there, remains and debris will be taken to the north-eastern coastal city of Recife for identification.

Air France Flight 447 emitted its last signals roughly 400 miles (640 km) north-east of the Fernando de Noronha islands.The Pentagon has said there are no signs of terrorism. Brazil's defence minister said the possibility was never considered. French foreign minister, Bernard Kouchner, agreed that there is no evidence supporting a "terrorism theory", but said that "we cannot discard that for now".